Semiconductor device washing apparatus and a method of washing a semiconductor device

ABSTRACT

A semiconductor device washing apparatus washes a surface of a semiconductor wafer after a chemical mechanical polishing process is performed for the surface. A roll brush is placed on the surface of the semiconductor wafer so as to contact with the surface. A first chemical liquid tank contains first chemical liquid. A first exhaust nozzle sprays the first chemical liquid onto the surface of the semiconductor wafer. A second chemical liquid tank contains second chemical liquid. A second exhaust nozzle sprays the second chemical liquid onto the surface of the semiconductor wafer. The first chemical liquid and the second chemical liquid are splayed onto the surface of the semiconductor wafer on the condition that the roll brush and the semiconductor wafer are rotated.

This application is a division of application Ser. No. 09/316,248, filedMay 21, 1999, now U.S. Pat. No. 6,241,584.

BACKGROUND OF THE INVENTION

This invention relates to a semiconductor device washing apparatus and amethod of washing the semiconductor device after a Chemical MechanicalPolishing (CMP) process.

Conventionally, irregularities are often formed on a surface of asemiconductor device having a laminate structure in a step ofmanufacturing the semiconductor device. The surface having theirregularities is flattened by the use of the known CMP (ChemicalMechanical Polishing) process.

This polishing process is generally carried out by using solutioncontaining dense polishing particles (for example, silica particles,alumina particles) during the CPM process. These particles must bealmost completely removed from a wafer surface after the CMP process tokeep reliability of an electronic device and a desired cleaning degreeof a manufacture line.

In particular, when a hydrophobic film, such as, a silicon nitride filmand a polysilicon film, is polished, it is difficult to remove particleswhich are left on the hydrophobic surface in comparison with ahydrophilic surface. Therefore, a washing method of effectively removingthe particles has been required.

A brush scrub method using a sheet-fed type spin washing apparatus isgenerally used as the method of removing the particles which are left onthe wafer after the CMP process.

For example, the spin washing apparatus includes a roll blush 12, anexhaust nozzle 13, a chemical liquid tank 15, and a pure water exhaustnozzle 14, as illustrated in FIG. 1.

In this event, the roll brush 12 removes particles which are left on awafer 11. In the exhaust nozzle 13, an exhaust hole is opposite to thewafer 11. Further, chemical liquid is contained in the chemical liquidtank 15. The chemical liquid is injected or sprayed from the exhausthole towards or onto the wafer 11. Moreover, pure water is injected orsprayed from an exhaust hole of the pure water exhaust nozzle 14 towardsor onto the wafer 11.

In the above-mentioned spin washing apparatus, the roll brush 12 iscontacted with the wafer 11. The washing water is supplied from thechemical liquid tank 15 towards the wafer 11 through the exhaust nozzle13.

Under this circumstance, the wafer 11 is washed by pure water which isinjected from the pure water exhaust nozzle 14 on the condition that thewafer 11 and the roll brush 12 are rotated.

In this case, dilution ammonia solution (I. J. Malik et al.: MRS. Symp.Proc. Vol. 386, p.109 (1995)) or dilution hydrofluoric acid solution isused as the washing water other than the pure water. However, thesesolutions are not effective for washing the above-mentioned hydrophobicsurface.

In contrast, a report has been made about an example in whichhydrophobic property is improved to enhance the removing effect (orperformance) by adding detergent during the CMP process and thesubsequent washing process in the 57th prof. (p. 637, 8p-L-7) of [TheJapan Society of Applied Physics]. Herein, it is to be noted that a maincomponent of the washing solution may be uncertain in theabove-mentioned report.

Further, disclosure has been made about a conventional example forobtaining a hydrophilic surface by adding alcohol liquid during the CMPprocess in Japanese Unexamined Patent Publication (JP-A) No. Hei.9-277172.

However, the ammonia solution or the dilution hydrofluoric acid solutiondoes not have capability for obtaining the hydrophilic surface.Consequently, it is not sufficiently effective to wash the hydrophobicsurface.

On the other hand, although the ammonia water containing the detergentis effective, there is the following problem. Namely, it is easy thathigh-polymer organic substance constituting the detergent is left on thewafer after the washing process. Consequently, a washing step forremoving the organic substance further becomes necessary.

Further, if a proper liquid wasting process is not performed for thedetergent, the detergent gives an adverse effect for the environment. Inconsequence, it is necessary to prepare an expensive processing facilityto carry out the proper process.

With respect to the example for adding the alcohol during the CMPprocess, the alcohol serves as a first washing liquid in a polishingapparatus for performing the CMP process. However, the alcohol does notserve as a final washing liquid for the subsequent step of depositing afilm.

In general, the washing process in the polishing apparatus accompanieswith contaminants inside the apparatus. Consequently, high cleaningwashing can not be performed. As a result, an additional polishingapparatus is required to be arranged independently of the subsequentwashing apparatus.

Further, when the hydrophobic surface, such as, the silicon nitride filmand the polysilicon film, is exposed after the CPM process, it isdifficult to remove the particles which are left on the hydrohobicsurface as compared to the hydrophilic surface.

Therefore, a washing method for effectively removing the particles hasbeen required.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a semiconductordevice washing apparatus which is capable of improving removingperformance of polishing particles.

It is another object of this invention to provide a semiconductor devicewashing apparatus in which particles almost does not remain on a waferafter a CMP process.

It is further object of this invention to provide a semiconductor devicewashing apparatus which is capable of readily processing wasting liquid.

According to this invention, a semiconductor device washing apparatuswashes a surface of a semiconductor wafer after a chemical mechanicalpolishing process is performed for the surface.

Under this circumstance, a roll brush is placed on the surface of thesemiconductor wafer so as to contact with the surface.

Further, a first chemical liquid tank contains first chemical liquid. Afirst exhaust nozzle sprays the first chemical liquid onto the surfaceof the semiconductor wafer.

Moreover, a second chemical liquid tank contains second chemical liquid.A second exhaust nozzle sprays the second chemical liquid onto thesurface of the semiconductor wafer.

With such a structure, the first chemical liquid and the second chemicalliquid are splayed onto the surface of the semiconductor wafer on thecondition that the roll brush and the semiconductor wafer are rotated.

In this condition, polishing particles are left on the surface of thesemiconductor wafer after the chemical mechanical polishing process. Theroll brush removes the polishing particles from the surface of thesemiconductor wafer.

In this case, the first exhaust nozzle has a first exhaust hole whilethe second exhaust nozzle has a second exhaust hole. Each of the firstexhaust hole and the second exhaust hole is opposite to the surface ofthe semiconductor wafer. The first chemical liquid is sprayed onto thesurface via the first exhaust hole while the second chemical liquid issprayed onto the surface via the second exhaust hole.

In this event, the first chemical liquid comprises ammonia liquid whilethe second chemical liquid comprises alcohol liquid.

The ammonia liquid preferably comprises lower alcohol. In this event,the lower alcohol may be at least one selected from the group consistingof ethanol, methanol, and isopropyl alcohol.

Herein, the surface of the semiconductor wafer is hydrophobic. Thehydrophobic surface is changed into a hydrophilic surface by the use ofthe alcohol liquid. In this event, the hydrophobic surface is changedinto the hydrophilic surface in order to enhance removing performance ofthe polishing particles which are left on the semiconductor surface. Thehydrophobic surface may comprise a surface in which a silicon nitridefilm or a polysilicon film is exposed.

Thus, the hydrophobic wafer surface is changed into the hydrophilicsurface by adding the alcohol liquid, as mentioned before. Thereby, theremoving performance of the particles is largely improved.

Further, the alcohol liquid is consisted of low molecular as compared tothe detergent. Consequently, it is difficult that the particles are lefton the wafer after the CMP process. Moreover, the alcohol liquid can bereadily wasted in comparison with the detergent.

Moreover, this invention is effective for the wafer having the exposedsurface which readily becomes hydrophobic, such as, the silicon nitridefilm and the polysilicon film after the CMP process. Under thiscondition, the polishing particles, which are left on the wafer, can beeffectively removed.

Consequently, reliability of the semiconductor device can be enhanced.Further, cross contamination of the manufacturing line can beeffectively suppressed. As a result, the manufacturing yield can beimproved.

Moreover, the substance, such as, the detergent is not used in thisinvention. This is because it is difficult to waste the detergent. Inconsequence, the environment is not destroyed, and cost for wastingwashing liquid can be largely reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structure diagram showing an example of aconventional brush scrub washing apparatus;

FIG. 2 is a schematic structure diagram showing a semiconductor devicewashing apparatus according to a first embodiment of this invention;

FIG. 3 is a schematic structure diagram showing a semiconductor devicewashing apparatus according to a second embodiment of this invention;and

FIG. 4 is a graph showing removing result of particles in accordancewith the semiconductor device washing apparatus illustrated in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 2, description will be made about a semiconductordevice washing apparatus according to a first embodiment of thisinvention.

In the first embodiment, a sheet-fed type and roll type of brush scrubwashing apparatus is used after Chemical Mechanical Polishing (CMP)process.

The washing apparatus includes a roll blush 2, a first exhaust nozzle 6,a chemical liquid tank 8, and a pure water exhaust nozzle 4, a secondexhaust nozzle 7, and a second chemical liquid tank 9, as illustrated inFIG. 2.

In this event, the roll brush 2 removes particles which are left on asemiconductor wafer 1. In the first exhaust nozzle 6, an exhaust hole isopposite to the wafer 1. Further, first chemical liquid is contained inthe first chemical liquid tank 8. The first chemical liquid contained inthe first chemical liquid tank 8 is injected or sprayed from the exhausthole towards or onto the wafer 1.

Moreover, pure water is injected or sprayed from an exhaust hole of thepure water exhaust nozzle 4 towards or onto the wafer 1. Further, secondchemical liquid is contained in the second chemical liquid tank 9. Thesecond chemical liquid contained in the second chemical liquid tank 9 isinjected or sprayed from the exhaust hole towards or onto the wafer 1.

In this case, the first chemical liquid includes ammonia liquid whilethe second chemical liquid includes alcohol liquid.

In the above-mentioned washing apparatus, the roll brush 2 is contactedwith the wafer 1. On this condition, The first chemical liquid and thesecond chemical liquid (namely, washing water) are supplied from thefirst chemical liquid tank 8 and the second chemical liquid tank 9towards the wafer 1 through the first exhaust nozzle 6 and the secondexhaust nozzle 7.

Under this circumstance, the wafer 1 is washed by pure water which isinjected from the pure water exhaust nozzle 4 on the condition that thewafer 1 and the roll brush 2 are rotated.

With such a structure, ammonia liquid (for example, ammonia liquid of0.05%) from the first chemical liquid tank 8 is supplied onto the wafer1 through the first exhaust nozzle 6 on the condition that the wafer 1and the roll brush 2 are rotated. Herein it is to be noted that asurface of a silicon nitride film is exposed on the wafer 1.

At the same time, the alcohol liquid (for example, alcohol liquid of0.1%) from the second chemical liquid tank 9 is supplied onto the wafer1 through the second exhaust nozzle 7.

After the washing process (for example, about 40 seconds), the purewater is supplied onto the wafer 1 through the pure water exhaust nozzle4 to perform a rinse process (for example, about 20 seconds).

In this event, the first chemical liquid, the second chemical liquid andthe pure water may not be directly supplied onto the wafer 1, and may bedropped onto the roll brush 2. The processed wafer 1 is transferred toadjacent washing chamber (not shown).

Alternatively, the alcohol liquid may be first supplied from the secondexhaust nozzle 7 onto the wafer 1 for first 10 seconds to change thesurface of the wafer 1 into the hydrophilic surface in the sequence ofthe washing process. Thereafter, the ammonia liquid may be supplied fromthe first exhaust nozzle 6 for the subsequent 40 seconds to perform thewashing process.

In this case, the alcohol liquid includes lower alcohol liquid. Thislower alcohol liquid includes ethanol, methanol, or isopropyl alcohol(IPA). Herein, concentration of the ammonia liquid preferably fallswithin the range between 0.001% and 10% while concentration of thealcohol liquid desirably falls within the range between 0.005% and 10%.

Subsequently, description will be made about a semiconductor devicewashing apparatus according to a second embodiment of this inventionwith reference to FIG. 3.

In the second embodiment, chemical liquid is supplied from an internalof a roll brush 2. For example, ammonia liquid from a first chemicalliquid tank 8 and isopropyl alcohol (IPA) from a second chemical liquidtank 9 are mixed in a tube 10, and is supplied to the internal of theroll brush 2 through the tube 10.

The supplied chemical liquid is injected or sprayed onto the wafer 1from fine holes which are arranged or opened on the roll brush 2.Herein, it is to be noted that a silicon nitride film surface is exposedon the wafer 1. In this example, each chemical liquid may be suppliedwith the above-mentioned time difference, like the first embodiment.

The alcohol liquid preferably includes lower alcohol, such as, methanolor ethanol. Herein, concentration of the ammonia liquid preferably fallswithin the range between 0.001% and 10% while concentration of thealcohol liquid desirably falls within the range between 0.005% and 10%.

Although the chemical liquid is supplied from the internal of the rollbrush 2 onto the wafer 1, the chemical liquid may be dropped onto theroll brush 2 in the second embodiment.

Further, the brush is not limited to the roll type, but it may be a disktype or a pen type.

Moreover, this invention is also effective for the wafer 1 having anexposed surface which readily becomes hydrophobic, such as, apolysilicon film other than the silicon nitride film surface.

In FIG. 4, a result, which is experimented using the washing apparatusaccording to the first embodiment, is illustrated.

First, the wafer 1 was washed after the CMP process was carried out forthe silicon nitride film. Thereafter, the number of the silica particles(0.2 μm or more in particle diameter), which are left on the wafer 1,was measured.

As a result, the particles having the number of 380/wafer in averagewere left on the wafer in the conventional washing apparatus using theammonia liquid, as illustrated in FIG. 4.

In contrast, the particles having the number of 32/wafer in average wereleft on the wafer in the washing apparatus according to this inventionusing IPA and the ammonia liquid, as illustrated in FIG. 4.

Thus, it is found out that from FIG. 4 that the remained number of theparticles in this invention is considerably smaller than that in theconventional case.

What is claimed is:
 1. A semiconductor device washing apparatus whichwashes a surface of a semiconductor wafer after a chemical mechanicalpolishing process is performed for the surface, comprising: a roll brushwhich is placed on the surface of the semiconductor wafer so as tocontact with the surface; a first chemical liquid tank which containsfirst chemical liquid; a first exhaust nozzle which sprays the firstchemical liquid onto the surface of the semiconductor wafer; a secondchemical liquid tank which contains second chemical liquid; and a secondexhaust nozzle which sprays the second chemical liquid onto the surfaceof the semiconductor wafer; the first chemical liquid and the secondchemical liquid being sprayed onto the surface of the semiconductorwafer simultaneously on the condition that the roll brush and thesemiconductor wafer are rotated.
 2. An apparatus as claimed in claim 1,wherein: polishing particles are left on the surface of thesemiconductor wafer after the chemical mechanical polishing process, andthe roll brush removes the polishing particles from the surface of thesemiconductor wafer.
 3. An apparatus as claimed in claim 1, wherein: thefirst exhaust nozzle has a first exhaust hole while the second exhaustnozzle has a second exhaust hole, each of the first exhaust hole and thesecond exhaust hole being opposite to the surface of the semiconductorwafer, and the first chemical liquid is sprayed onto the surface via thefirst exhaust hole while the second chemical liquid is sprayed onto thesurface via the second exhaust hole.
 4. An apparatus as claimed in claim1, wherein: the first chemical liquid comprises ammonia liquid while thesecond chemical, liquid comprises alcohol liquid.
 5. An apparatus asclaimed in claim 4, wherein: the ammonia liquid comprises lower alcohol.6. An apparatus as claimed in claim 5, wherein: the lower alcoholcomprises at least one selected from the group consisting of ethanol,methanol, and isopropyl alcohol.
 7. An apparatus as claimed in claim 4,wherein: concentration of the ammonia liquid falls within the rangebetween 0.001% and 10%.
 8. An apparatus as claimed in claim 4, wherein:concentration of the alcohol liquid falls within the range between0.005% and 10%.
 9. An apparatus as claimed in claim 4, wherein: thesurface of the semiconductor wafer is hydrophobic, and the hydrophobicsurface is changed into a hydrophilic surface by the use of the alcoholliquid.
 10. An apparatus as claimed in claim 9, wherein: the hydrophobicsurface is changed into the hydrophilic surface in order to enhanceremoving performance of the polishing particles which are left on thesemiconductor surface.
 11. An apparatus as claimed in claim 9, wherein:the hydrophobic surface comprises a surface in which a silicon nitridefilm or a polysilicon film is exposed.
 12. An apparatus as claimed inclaim 1, further comprising: a third exhaust nozzle which sprays purewater onto the surface of the semiconductor wafer.
 13. An apparatus asclaimed in claim 12, wherein: the first liquid, the second liquid andthe pure water are dropped onto the roll brush.
 14. A semiconductordevice washing apparatus which washes a surface of a semiconductor waferafter a chemical mechanical polishing process is performed for thesurface, comprising: a roll brush which is placed on the surface of thesemiconductor wafer so as to contact with the surface, the roll brushhaving a plurality of fine holes; a first chemical liquid tank whichcontains first chemical liquid; a second chemical liquid tank whichcontains second chemical liquid; and a tube which mixes the firstchemical liquid with the second chemical liquid and which supplies themixed liquid inside the roll brush; the mixed liquid being sprayed ontothe surface of the semiconductor wafer through the fine holes of theroll brush on the condition that the roll brush and the semiconductorwafer are rotated, the first chemical liquid comprises ammonia liquidwhile the second chemical liquid comprises alcohol liquid, and theammonia liquid comprises lower alcohol.
 15. An apparatus as claimed inclaim 14, wherein: polishing particles are left on the surface after thechemical mechanical polishing process, and the roll brush removes thepolishing particles from the surface of the semiconductor wafer.
 16. Anapparatus as claimed in claim 14, wherein: the lower alcohol comprisesat least one selected from the group consisting of ethanol, methanol,and isopropyl alcohol.
 17. An apparatus as claimed in claim 14, wherein:concentration of the ammonia liquid falls within the range between0.001% and 10%.
 18. An apparatus as claimed in claim 14, wherein:concentration of the alcohol liquid falls within the range between0.005% and 10%.
 19. An apparatus as claimed in claim 14, furthercomprising: a third exhaust nozzle which sprays pure water onto thesurface of the semiconductor wafer.
 20. An apparatus as claimed in claim14, wherein: the surface of the semiconductor wafer is hydrophobic, andthe hydrophobic surface is changed into a hydrophilic surface by the useof the alcohol liquid.
 21. An apparatus as claimed in claim 20, wherein:the hydrophobic surface is changed into the hydrophilic surface in orderto enhance removing performance of the polishing particles.
 22. Anapparatus as claimed in claim 20, wherein: the hydrophobic surfacecomprises a surface in which a silicon nitride film or a polysiliconfilm is exposed.